The idea of harnessing the energy "free" in the air by using the passing wind to rotate a shaft in order to produce useful work has long intrigued the inventive mind and for many centuries now been realized in a variety of forms. In the recent past, the advent of electrical energy and abundant fossil fuels resulted, in the most part, in the relegation of devices for harnessing wind forces to museums and country-side oddities.
During the past several years, however, the recognition of the limited supply of fossil fuels and the soaring costs of energy in general have created a renaissance in "wind machines" all seeking to extract energy from the passing air with sufficient efficiency to constitute practical sources of electrical and mechanical power.
In its simplest form, a "wind machine" comprises a shaft which carries sails or blades or other means of catching the wind and rotating the shaft from which mechanical or electrical power is generated. Within given limits the velocity with which the shaft rotates is roughly proportional to the velocity of the wind acting on the shaft's rotators and to the amount of energy produced. The faster the shaft rotates for a given velocity of wind and a given load, the greater is the efficiency with which wind energy is converted into mechanical or electrical energy.
It has thus been one approach to increasing the efficiency of wind generating machines to increase the efficiency of the rotation of the working shaft for a given wind velocity.
In U.S. Pat. No. 4,204,799 to de Geus, issued May 27, 1980, increased efficiency is purported to result from the disposition of a diffusor positioned downstream of the working blades which forms a venturi which decreases the downstream pressure so as to "pull" the air through the blades and thereby render them more efficient. Similarly, in U.S. Pat. No. 4,166,596 to Mouton, Jr., et al., issued Sept. 4, 1979, a "vena contracta" is disposed downstream of the turbine section of the power generator so as to create an area of reduced pressure to facilitate the air passing through the generator and thereby add to the efficiency of the energy extracted from the wind.
U.S. Pat. No. 4,258,271 to Chappell, et al., issued Mar. 24, 1981, also speaks of reducing the downstream pressure and thereby increasing the power output of an impeller mounted to catch the wind (or other fluid) and produce energy.
None of the references mentioned above, nor any others known to applicant disclose a means for reducing downstream pressure which includes a low pressure chamber for receiving turbine exhaust air or means for adjusting the mechanism which reduces the downstream pressure as is taught by the present invention. Other features of the present invention also not disclosed by any known prior art further increase the efficiency with which the present invention extracts energy from the air and converts it to electrical or mechanical power.